these 5 derivations will be built:
  /nix/store/hqqk7a6whhdym2jh02bkj8kmi8cwlp3m-tree_style_tab-4.4.4.xpi.drv
  /nix/store/78g80qzacvq4vxa4dlr3a6h6d8hd0q4d-tree-style-tab-4.4.4.drv
  /nix/store/qla8aymcf3v6q1k8gps7g2dwbdfgxnw8-hm-firefox-extensions.drv
  /nix/store/300l9i7al6gs4ba040md35vsmgddqrs0-home-manager-files.drv
  /nix/store/8mjbjlwzpzz1kdp22ncgsb8yhyp09z9j-home-manager-generation.drv